All
movements
are
due
to
to
the
joint
action
of
____________________
or
more
____________________
muscles
.
____________________
muscles
act
in
the
same
direction
.
____________________
muscles
,
working
in
____________________
,
work
in
opposite
directions
.
If
one
contracts
,
the
other
____________________
and
vice
versa
.
The
bones
,
muscles
and
____________________
involved
in
producing
movement
act
as
a
____________________
.
Three
types
of
____________________
exist
based
on
the
postion
of
three
elements
.
____________________
:
where
the
force
is
applied
.
____________________
:
where
the
part
to
be
moved
is
located
.
____________________
:
where
the
lever
is
supported
.
In
our
body
we
can
find
____________________
class
____________________
(
like
the
one
formed
by
the
head
and
the
spinal
column
)
,
____________________
class
____________________
(
like
the
one
formed
by
the
ankle
and
the
leg
)
and
____________________
class
____________________
(
like
the
one
formed
by
arm
and
the
forearm
)
.
